Our proposed project, Gold nanoparticle-based mercury analyzer for on-site measurements of soil and sediment, will develop a powerful and portable mercury analyzer. This project will continue the work from Phase I, by combining the nanoparticle based detector with a thermal/catalytic sample introduction system. Gold nanoparticle-based plasmonic mercury sensing is inexpensive, ultra-sensitive, and ideal for portable applications. The thermal/catalytic sample introduction system will be low power, with low sample loss and high throughput; it also does not require the use of wet chemicals or other consumables. The commercial instrument resulting from combining these two subsystems will be lightweight (<20lbs), sensitive to levels of concern for remediation (<6mg/kg Hg), and operate on battery power. Extensive field-testing will be conducted to ensure the mercury sensor is suitable for replacing the current costly and time-consuming laboratory methods. The development of such a device will benefit all parties concerned with mercury monitoring and the remediation of contaminated sites. Mercury monitoring costs hundreds of millions of dollars a year across diverse scientific, industrial, and regulatory groups. The fundamental issue these groups address is protecting human health, and the environment, from the risks of mercury pollution.